The ability to detect and respond to chemical signals is essential for animal survival. The gustatory system is primarily involved in feeding decisions, allowing animals to distinguish foods that are nutritious versus those that are toxic. How the detection of gustatory cues in the periphery is processed by the brain to elicit appropriate feeding decisions is not understood in any organism. The gustatory system of Drosophila provides an excellent model for studies of taste detection and feeding behavior because it is associated with well-defined chemical cues, robust behavioral responses and a complex nervous system that is amenable to molecular, genetic and electrophysiological approaches. The long-term objective of this proposal is to increase understanding of the neural pathways that regulate food intake, crucial for devising rational approaches to manipulate feeding decisions. Aim 1 will examine the anatomy and potential connectivity of candidate second- order taste neurons to provide a framework for understanding gustatory processing. Aim 2 will test whether second-order neurons integrate information across taste modalities or whether they are modality-selective. This will provide important insight into how taste cues are encoded in the brain. Aim 3 will test the hypothesis that candidate second-order taste neurons function in feeding decisions, by examining the behavioral consequences of manipulating activity selectively in second-order neurons. The proposed molecular genetics, cellular and behavioral approaches will provide a comprehensive analysis of taste processing that is difficult to achieve in other systems. These studies will provide insight into how gustatory information is processed in the brain and are an essential foundation for understanding insect feeding, relevant to limiting the spread of insect-borne disease.